ESCRIPTION: (adapted from the applicant's abstract) Donald Monkhouse of herics, Inc. submits this Phase I application to develop an implantable ong term, biodegradable delivery system for ethinyl estradiol. Past ttempts to produce such systems have been unsuccessful because they rovided only short periods of variable drug delivery and non-reproducible iodegradation characteristics. The applicant states that there is, herefore, a currently unmet need for long term delivery systems that can e used in postmenopausal estrogen replacement therapy. This need might e met, he believes by implanting biodegradable polymers that delivery rug with zero-order kinetics. Such a system could be fabricated using heriFormTM technology to construct the polymer implants. During Phase I he applicant intends to design and fabricate four different implants, ach of which has unique internal architecture, spatial distribution of rug and excipient chemistry. His specific aims, during this effort, nclude 1) selecting appropriate excipient materials for four individual tructural implant designs, 2) evaluation of these prototypes for rate and xtent of estrogen release plus polymer degradation in vitro, and 3) evelopment of alternative design options for the best candidate rototypes through mathematical analysis of the initial data using heriSysTM expert, a design program. This plan it expected to provide a elivery system that can then be tested in vivo during a Phase II study. PROPOSED COMMERCIAL APPLICATION: Potential commercial application not available.